Given the enormous public health problem that depressive disorders represent there is significant benefit to be derived from the identification of depression vulnerability (DV) risk factors, including the development of preventive interventions. Recent research has found that allelic variation in the serotonin transporter gene-linked polymorphic region (5-HTTLPR) is related to depression outcomes under conditions of stress, with greater DV associated with the short (s) versus long (I) allele. For the current proposal a genetic high-risk design will be used: Individuals will be recruited who have the "high DV risk" (s/s) or "low DV risk" (I/I) genotype. The major aim of the proposal is to test the hypothesis that short-term mood-related behavioral outcomes vary as a function of an individual's 5-HTTLPR genotype, with poorer (i.e., DV) outcomes associated with the short (s) versus long (I) allele. These outcomes include, among others, greater reactivity to negative mood inducing events and poorer ability to recover from an acute negative mood. The identification of these hypothesized behavioral differences would represent significant progress toward developing interventions that reduce the risk of depression in those individuals identified as "at risk."